How to Increase the Rate of a Solute to Dissolve

The rate at which a solid dissolves in a liquid is tied to several factors.

Dissolving is a familiar process. Salt, for example, dissolves readily in water, as does sugar in coffee. On a molecular level, dissolving consists of the molecules of a solute -- salt or sugar -- encountering and pairing up with the molecules of a solvent -- water or coffee. Only when a successful pairing is made can the solute dissolve into the solvent. To increase the rate at which a solute dissolves, you must increase the rate at which molecules within the solute can encounter and subsequently pair with molecules within the solvent.

Things You'll Need

• Knife
• Mortal and pestle or blender
• Pan and stove
• Microwave and microwavable container

Instructions

1. Crush the solute into smaller pieces. Cut the solute into smaller pieces using a knife if it consists of large, solid pieces. Grind the solute down using a mortar and pestle, or pulverize it using a blender if it consists of small pieces. For example, to increase the rate at which table salt dissolves in water, use a mortar and pestle to crush the salt crystals into smaller crystals.

   Crushing the solute increases the rate at which it dissolves by increasing its surface area. Increasing the number of molecules of the solute that can come into contact with molecules of the solvent at any given time increases the opportunity for successful pairing of solute and solvent molecules, increasing the rate of dissolution.

2. Heat the solvent. Pour the solvent into a pan and place the pan over low heat for about a minute. Use a thermometer to check the temperature of the solvent to ensure that it is rising.

   Use a microwave to heat the solvent if you do not have a pan and stove available. Place the solvent in a microwavable container and place it in the microwave on high heat for 10 seconds. Touch the side of the container to check if the solvent has warmed. Make sure your solvent is microwave safe before warming it up in the microwave.

   Warming the solvent increases the speed of the molecules within the liquid. This increases the rate at which the solute dissolves by increasing the rate at which the molecules in the solvent collide and successfully pair with the molecules in the solute.

3. Continuously stir the solution as you add the solute to the solvent. Stirring increases the rate at which the solute dissolves by increasing the contact between the solute and the solvent, an effect similar to the effect of crushing the solute into smaller pieces.

Tips & Warnings

• Be careful of solute toxicity if you're planning on crushing or pulverizing it. Crushing it may increase your risk of inhaling it or of having it come in contact with your skin.

• Be careful of the solvent's toxicity and boiling point if you're heating it. The hotter the solvent is, the more likely you are to inhale or come in contact with its fumes.

References

• University of Leicester; Particle Theory; November 2000
• Clinton Community College; Chemistry; Michael J. Gregory, Ph.D.
• Argonne National Laboratory: Stirring and Dissolving Rate
• National Aeronautics and Space Administration: Reaction Rates
• Saskatchewan Schools: Factors Affecting Solubility